cvedb.io
CVE-2025-24356
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2025-01-27T18:15:41.347 · Last modified 2026-06-17T08:58:37.750

Summary

fastd is a VPN daemon which tunnels IP packets and Ethernet frames over UDP. When receiving a data packet from an unknown IP address/port combination, fastd will assume that one of its connected peers has moved to a new address and initiate a reconnect by sending a handshake packet. This "fast reconnect" avoids having to wait for a session timeout (up to ~90s) until a new connection is established. Even a 1-byte UDP packet just containing the fastd packet type header can trigger a much larger handshake packet (~150 bytes of UDP payload). Including IPv4 and UDP headers, the resulting amplification factor is roughly 12-13. By sending data packets with a spoofed source address to fastd instances reachable on the internet, this amplification of UDP traffic might be used to facilitate a Distrib

Affected products

fastd_project — fastd

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.